In offices having large numbers of files, there are numerous times when inordinate amounts of time are required to locate files that are either misfiled or located in any one of a number of places where they may be used. It is imperative, in some circumstances, that a file be located quickly.
In known object locating systems, a searcher is used that emits either radio frequency, light or sonic waves to which a transponder in the object being sought audibly responds so as to indicate its location. In one of the systems described in U.S. Pat. No. 4,476,469, for example, pulse position modulated radio frequency waves are transmitted by a hand held searcher, and a transponder in the object being searched produces a series of audible tones in response to a particular pulse position modulation. The transponder includes all of the stages of a radio receiver for deriving the transmitted coded information so that it is expensive. Furthermore, it is stated that satisfactory operation up to 20 feet was not attained owing to the fact that the transmitted signal strength falls off rapidly with distance. This suggested that sonic or ultrasonic rather than RF waves should be transmitted by the searcher, but they would be severely attenuated by paper files so as not to be useful in searching for a file that may be in a stack.
Bayer, U.S. Pat. No. 4,507,653, discloses an integrated circuit receiver including audio detecting means, and an audio transducer for producing an audible sound. Bayer's device is designed to be attached to address books, daily schedule books, passports, credit cards holders, billfolds, eyeglasses, keys, and other such objects as discussed in column 3, lines 59 through 65. Each receiving unit includes an audio detector that is responsive to human-generated sounds such as a particular sequence of clapping noises, for producing a binary or electronically generated pulse whenever the appropriate sequence of sound waves are received, whereby the binary pulse is applied to a detection circuit for producing a plurality of second signals which are applied to a transducer for generating audible tones, thereby permitting a lost object to be uncovered.
Anderson, et al., U.S. Pat. No. 4,101,873 discloses a system for locating misplaced objects that includes miniaturized receivers that are activated by radio signals from a transmitter, for emitting audible tones to locate the missing object. The range of the system is about 300 ft. The receivers are designed to be activated by a signal of a particular frequency, for in turn activating an acoustic generator to emit a sound wave of a frequency in the more sensitive frequency region of human hearing. The transmitter is a tone generator, whereby the transmission signals will be of various tones for activating receivers that are designed to receive a particular combination of tones.
In most filing systems there are a large number of files that are continually changing so that it would be highly advantageous to be able to easily assign addresses to the new files. Unfortunately, in the location systems of the aforesaid patents there is no way of changing the address of an object by operation of the searcher.
Furthermore, the components serving as transponders in prior systems are far too thick to be used in a file.